I haven't been happy with the way my HWK-15 was performing (2 Dayton Series II drivers, both magnets in center), ever since I tested it with the two drivers clamshelled in the bottom baffle. The response in that case was much lower, great for HT/LFE but peaking a bit too low for music. With the drivers as they are now, bass is tight and reasonably musical but the extension is not as low. I'm hoping that the HWK-18 with the EV drivers will cover most of the musical requirements, allowing me to switch the HWK-15 back to the clamshell-in-lower-baffle configuration just to cover the bottom octave. With an Fs of 19Hz, the Daytons are pretty well suited to that purpose.

I built an HWK-18 with four JBL 2245H drivers. The bass is very extended. Assuming your HWK-18 is for home use, I would make sure I use drivers with a resonant frequency of 20 Hz or lower. This will ensure you get the DEEP bass response needed in home theater applications.

I have two of the EVX-180B in my home theater system. I have each one in a 18" Super Scooper. They are being pushed by a Phonic 3200 amp, running in parallel. So I'm push 2800 watts to them. Playing rock music thru them and I knock pictures off the wall in my living room and can hear them at my next door neighbors house hitting lowes.

The speaker is great and I have always wanted to build a HWK-18 for them but never have. Let me know what they sound like.